1. Field of the Invention
The invention is related to the field of communications, and in particular, to technologies for handling emergency telephone calls placed over packet networks.
2. Description of the Prior Art
The Public Switched Telephone Network (PSTN) provides emergency telephone calling services. On an emergency telephone call, the caller places a telephone call to the PSTN using an emergency telephone number such as 911. The PSTN processes the emergency telephone number to connect the caller to an emergency service. The emergency service typically includes emergency operators and emergency response units. The emergency operators answer the emergency telephone calls and provide an interface between the caller and the emergency response units. The emergency response units include fire departments, police departments, ambulance services, and other groups that respond to emergency situations.
There are several different emergency services that typically serve different geographic areas. On emergency telephone calls, the PSTN processes caller telephone numbers to route the emergency telephone call to the proper emergency service for the caller's geographic location. The PSTN also provides the caller telephone numbers to the emergency service, and the emergency service translates the caller telephone numbers into geographic addresses. In this way, emergency response units may travel to the geographic locations of the callers—even if the callers are unable to provide their current location.
For example, if the caller places an emergency telephone call from their home, the PSTN processes the caller's home telephone number to route the emergency telephone call to the emergency service that serves the caller's home location. The PSTN also transfers the caller's home telephone number to this emergency service. The emergency service processes the caller's home telephone number to determine the caller's home address. Emergency response units can then travel to the caller's home even if the caller is unable to communicate their current location to the emergency operator.
When an emergency telephone call is placed from a mobile telephone, the PSTN determines the general location of the caller and routes the emergency telephone call to the emergency service for the general location. Since the telephone number of the mobile telephone does not indicate a caller location like a home telephone number, the emergency service is unable to consistently translate the mobile telephone number into a geographic address for the caller's current location. To address this situation, the PSTN notifies the emergency service that the emergency telephone call has been placed from a mobile telephone, and typically, the emergency operator asks the caller for their current location.
Access to packet networks such as the Internet is now available at multiple locations across a wide geographic area. Packet telephone services have been developed to allow telephone calls over the packet networks. On a packet telephone call, a packet telephone is coupled to a packet network interface. The packet telephone transfer a call request over the packet network to a service node. The service node extends the call request to a destination on the packet network or to a destination on the PSTN. For a destination on the PSTN, the packet telephone transfers call communications over the packet network to the service node, and the service node transfers the call communications to the destination over the PSTN. Likewise, the destination transfers call communications to the service node over the PSTN, and the service node transfers the call communications to the packet telephone over the packet network. Additional details for this type of conventional packet telephone call are discussed below with respect to FIG. 1.
Unfortunately, if a caller places an emergency telephone call from a packet telephone over a packet network, the service node may not be able to effectively determine the caller's location. For example, the caller may travel and stay in a hotel that has a packet network interface in the hotel room. If the caller uses a packet telephone to place an emergency telephone call from their hotel room, the service node cannot effectively determine the caller's location. Technologies are needed to address this situation.